No, it doesn't work like that. First of all you get a letter of intended prosecution. You have to fill in and send the attached form back to them to ensure the details are correct, eg your wife could have been driving. Once the police have had this back they'll assess if a SAC is suitable.
Pete
Pete is right, I got caught on the cat and fiddle run near Buxton (yes the average speed cameras work all the way up there) in January 61mph in a 50 zone. The cut off point for the course was 63mph.
I first got the letter to confirm it was me (in my company Transit!) then offered the course £85.00 and no points or contest it and go to court and lose the course option
The course was really good, full of drivers giving reasons why they shouldn't have been there but lucky I thought to be offered the course